In an economy which primitives are exactly those in Mirrlees (1971), we investigate the efficiency of labor income tax schedules derived under the equal sacrifice principle. Starting from a given government revenue level, we useWerning’s (2007b) approach to assess whether there is an alternative tax schedule to the one derived under the equal sacrifice principle that raises more revenue while delivering less utility to no one. For our preferred parametrizations of the problem we find that inefficiency only arises at very high levels of income. We also show how the multipliers of the Pareto problem may be extracted from the data and used to find the implicit marginal social weights associated with each level of income